I Don't Normally Play Electric-Type Characters...

[Arnabas]

... so can someone tell me what it represents when a blue circle appears around the button for Tesla Cage? 

I can't seem to find an explanation. 

[KaizenSoze]

You have maxed out the number of static stacks. Each stacks allows Tesla cage to jump from one mob to another.

 

But the range on Tesla Cage jumping is not large, so you'll rarely hit more than 3 mobs. Unless they are being grouped well.

 

 

[Arnabas]

Thanks. 

[Six-Six]

It means you're done charging. You can unplug now. 😃